Liquid crystal device and electronic apparatus

ABSTRACT

A liquid crystal device which has a first and second electrodes formed on a second substrate and which controls allows alignment of liquid crystal molecules by an electric field generated between the first and second electrodes, wherein the liquid crystal molecules in the liquid crystal layer are aligned in a first direction in a plane of the substrate, wherein a phase difference layer having molecules, which are inclined in the plane of the first or second substrate and are aligned in directions different from one another in the transmissive display portion and the reflective display portion, is formed on a surface of the first or second substrate opposed to the liquid crystal layer, and wherein a director of the molecules of the phase difference layer is aligned in a second direction parallel to the first direction at least in the plane of the transmissive display portion.

CROSS REFERENCES TO RELATED APPLICATIONS

The present application is a divisional of U.S. patent application Ser.No. 11/987,102 filed on Nov. 27, 2007, and claims priority to JapanesePatent Application JP 2007-045046 filed in the Japanese Patent Office onFeb. 26, 2007, the entire contents of which being incorporated herein byreference.

BACKGROUND

The present invention relates to a liquid crystal device used in apersonal computer, a cellular phone, or the like and an electronicapparatus using the liquid crystal device.

As a display device of an electronic apparatus such as a personalcomputer or a cellular phone, a liquid crystal device has been used. Inaddition, a transflective liquid crystal device is used to saveelectrical power in various circumstances such as outdoors or indoors.

Improvement in display quality or function of liquid crystal devices hasbeen demanded. For example, in order to improve a wide viewing angle, anin-plane switching (ISP) mode or the like is also used in thetransflective liquid crystal devices.

However, for example, when a phase plate is disposed over an entiresurface of upper and lower surfaces of a liquid crystal panel, a viewingangle dependency occurs due to the phase plate. Accordingly, an optimumcondition for a dark display may rapidly deteriorate as a viewing pointmoves away from a normal direction.

Therefore, there is disclosed a method in which a phase plate isdisposed in a reflective display portion of the transflective IPS mode,a polarizing plate is commonly used in the reflective display portionand a transmissive display portion and disposed over an entire surfaceof upper and lower portions of the liquid crystal panel, and the phaseplate is disposed on the inner surface of the liquid crystal panel to beformed only in the reflective display portion by performing patterning(for example, see JP-A-2005-338256 ([0013] and FIG. 2).

The wide viewing angle of the dark display of the transflective liquidcrystal device is improved to some extent by the above-described method.However, it may not be easy to perform the patterning of the phase plate(phase difference layer) only in the reflective display portion.Moreover, the wide viewing angle of the dark display may not besufficient.

SUMMARY

An advantage of some aspects of the invention is that it provides aliquid crystal device which can be easily manufactured and has animproved wide viewing angle by further preventing light leakage in ablack display, and an electronic apparatus using the liquid crystaldevice.

According to an aspect of the invention, there is provided a liquidcrystal device which has a liquid crystal layer interposed between afirst substrate and a second substrate, a plurality of pixels eachhaving a transmissive display portion and a reflective display portion,and first and second electrodes formed on the second substrate and whichcontrols allows alignment of liquid crystal molecules in the liquidcrystal layer by an electric field generated between the first andsecond electrodes, wherein the liquid crystal molecules in the liquidcrystal layer are aligned in a first direction in a plane of thesubstrate, wherein a phase difference layer having molecules, which areinclined in the plane of the first or second substrate and are alignedin directions different from one another in the transmissive displayportion and the reflective display portion, is formed on a surface ofthe first or second substrate opposed to the liquid crystal layer, andwherein a director of the molecules of the phase difference layer isaligned in a second direction parallel to the first direction at leastin the plane of the transmissive display portion.

“A first electrode” refers to, for example, a pixel electrode and “asecond electrode” refers to, for example, a common electrode. Inaddition, the term “inclined” refers to, for example, having a pretiltangle.

In the liquid crystal device with the above-described configuration, thephase difference layer is formed in the transmissive display portion anda reflective display portion of the liquid crystal layer of the firstand second substrates. Accordingly, it is possible to solve difficultyin forming the phase difference layer only in the reflective displayportion like in the known example and also reduce cost.

The alignment direction of the molecules of the phase difference layerin the transmissive display portion is different from that of themolecules of the reflective display portion. Accordingly, it is possibleto minimize effect of the phase difference layer in the transmissivedisplay portion.

For example, when substrate alignment of the phase difference layer isset so that alignment in the transmissive display portion is differentfrom that in the reflective display portion (so called multiplealignments), the molecules of the phase difference layer have thepretilt angle. In this case, a problem arises in that a viewing anglecharacteristic, particularly, in an oblique direction may deteriorate.

In order to solve the problem, the director of the molecules isconfigured to be, for example, parallel or anti-parallel to the firstdirection which is the alignment direction of the liquid crystalmolecules in the substrate surface, at least in the transmissive displayportion. Accordingly, the light leakage in the black display is reducedeven in the oblique view. By configuring the director to be parallel oranti-parallel to the first direction, in terms of the Poincare sphere,the sphere is a little swollen from the equator by the phase differencelayer. The polarization state becomes elliptically polarized light closeto the linearly polarized light, and thus the light leakage in the blackdisplay can be more suppressed. As a result, it is possible to obtain awider viewing angle characteristic.

According to the liquid crystal device with the above-describedconfiguration, a direction of the molecules in the phase differencelayer inclined in the plane of the surface of the first or secondsubstrate may be substantially equal to that of the liquid crystalmolecules in the liquid crystal layer inclined in the plane of thesurface of the first or second substrate. With such a configuration, interms of the Poincare sphere, the sphere is less swollen from theequator by the phase difference layer, compared to a case where thedirector is configured to be anti-parallel. Accordingly, thepolarization state becomes the elliptically polarized light close to thelinearly polarized light, and thus the light leakage in the blackdisplay can be more suppressed. As a result, it is possible to obtainthe wider viewing angle characteristic.

According to the liquid crystal device with the above-describedconfiguration, the second substrate may have an insulating layer betweenthe first and second electrodes. With such a configuration, when avoltage is applied, electric field formed between the first and secondelectrodes is considerably curved and the alignment direction of theliquid crystal molecules in the electrodes is controlled. In this way,it is possible to obtain the wider viewing angle characteristic.

According to the liquid crystal device with the above-describedconfiguration, the first substrate may have a polarizing plate on thesurface opposed to the liquid crystal layer and an absorption axis ofthe polarizing plate may be parallel to the first direction. With such aconfiguration, when a voltage is not applied between the first andsecond electrodes, the light transmitted through the liquid crystallayer is absorbed by the polarizing plate, thereby improving further theblack display.

According to the liquid crystal device with the above-describedconfiguration, an angle formed by the alignment direction of themolecules of the phase difference layer in the transmissive displayportion and the alignment direction of the molecules of the phasedifference layer in the reflective display portion may be about 67.5°.With such a configuration, the retardation of the liquid crystal layerin the reflective display portion can be configured to be about aquarter wavelength, thereby realizing the better black display.

According to the liquid crystal device with the above-describedconfiguration, retardations of the liquid crystal layer in thetransmissive display portion and the reflective display portion may beabout a half wavelength and about a quarter wavelength, respectively.With such a configuration, a phase difference of a quarter wavelengthoccurring between the transmissive display portion and the reflectivedisplay portion can be solved. Accordingly, it is possible tosimultaneously realize the black display in both the transmissivedisplay portion and the reflective display portion.

According to the liquid crystal device with the above-describedconfiguration, both the retardations of the phase difference layer inthe transmissive display portion and in the reflective display portionmay be about a half wavelength. With such a configuration, circularlypolarized light or elliptically polarized light can be realized by theliquid crystal layer in the reflective display portion. In addition,when the reflected light is incident to the polarizing plate, the lightbecomes the linearly polarized light in the direction of the absorptionaxis. In this way, it is possible to realize a more reliable blackdisplay.

According to the liquid crystal device with the above-describedconfiguration, the phase difference layer is formed by polymerizingliquid crystalline compounds. With such a configuration, it is easier tochange the alignment direction in the transmissive display portion andthe reflective display portion, thereby realizing the black display withless the light leakage.

According to another aspect of the invention, there is provided anelectronic apparatus comprising the liquid crystal device according tothe liquid crystal device with above-described configuration.

According to the above-described aspects of the invention, there isprovided the liquid crystal device which can easily obtain the sameadvantage as that obtained in a case where the phase difference layer isformed only in the reflective display portion, and which can improve thewide viewing angle by further preventing the light leakage. As a result,it is possible to provide the electronic apparatus capable of furtherimproving display quality at low cost.

Additional features and advantages are described herein, and will beapparent from the following Detailed Description and the figures.

BRIEF DESCRIPTION OF THE FIGURES

The invention will be described with reference to the accompanyingdrawings, wherein like numbers reference like elements.

FIG. 1 is a schematic top view illustrating a liquid crystal deviceaccording to a first embodiment.

FIG. 2 is a schematic sectional view illustrating the liquid crystaldevice taken along the line A-A shown in FIG. 1.

FIG. 3 is a diagram for explaining an absorption axis and a direction ofliquid crystal molecules and molecules according to the firstembodiment.

FIG. 4 is a diagram for explaining how light travels according to thefirst embodiment.

FIG. 5 is a diagram for explaining the absorption axis and the directionwhen a liquid crystal panel is viewed in an oblique direction accordingto the first embodiment.

FIG. 6 is a diagram for explaining a viewing angle characteristicaccording to a first example.

FIG. 7 is a diagram for explaining an absorption axis and a direction ofliquid crystal molecules and molecules according to a second example.

FIG. 8 is a diagram for explaining the viewing angle characteristicaccording to the second example.

FIG. 9 is a diagram for explaining the absorption axis and the directionwhen a liquid crystal panel is viewed in an oblique direction accordingto the second example.

FIG. 10 is a diagram for explaining an absorption axis and a directionof liquid crystal molecules and molecules according to a third example.

FIG. 11 is a diagram for explaining the viewing angle characteristicaccording to the third example.

FIG. 12 is a diagram for explaining an absorption axis and a directionof liquid crystal molecules and molecules according to a fourth example.

FIG. 13 is a diagram for explaining the viewing angle characteristicaccording to the fourth example.

FIG. 14 is a diagram for explaining an absorption axis and a directionof liquid crystal molecules and molecules according to a firstcomparative example.

FIG. 15 is a diagram for explaining the viewing angle characteristicaccording to the first comparative example.

FIG. 16 is a diagram for explaining an absorption axis and a directionof liquid crystal molecules and molecules according to a secondcomparative example.

FIG. 17 is a diagram for explaining the viewing angle characteristicaccording to the second comparative example.

FIG. 18 is a schematic top view illustrating a liquid crystal deviceaccording to a second embodiment.

FIG. 19 is a schematic sectional view illustrating the liquid crystaldevice taken along the line J-J shown in FIG. 18.

FIG. 20 is a schematic diagram illustrating an outer appearance of acellular phone according to a third embodiment.

FIG. 21 is a schematic diagram illustrating an outer appearance of apersonal computer according to a third embodiment.

DETAILED DESCRIPTION

Hereinafter, embodiments of the invention will be described withreference to the drawings. In the embodiments described below, as anexample of a liquid crystal device, a thin film transistor (TFT) activematrix type transflective liquid device and an electronic apparatususing the liquid crystal device will be described. However, theinvention is not limited thereto. Moreover, in order to enable easydescription of elements shown in the accompanying drawings, the elementsare appropriately shown with different scales and in different numbersfrom the actual ones.

First Embodiment

FIG. 1 is a schematic top view illustrating a liquid crystal deviceaccording to a first embodiment. FIG. 2 is a schematic sectional viewillustrating the liquid crystal device taken along the line A-A shown inFIG. 1. FIG. 3 is a diagram for explaining an absorption axis of apolarizing plate and a direction of liquid crystal molecules andmolecules according to the first embodiment. FIG. 1 shows a secondsubstrate in which an alignment film is removed for descriptiveconvenience.

Configuration of Liquid Crystal Device

As shown in FIG. 2, a liquid crystal device 1 includes, for example, aliquid crystal panel 2, a flexible substrate (not shown) connected tothe liquid crystal panel 2, an illuminating device 3 emittingilluminating light to the liquid crystal panel 2, and a case (not shown)holding the liquid crystal panel 2 and the illuminating device 3. Inthis case, in addition to the illuminating device 3, other supplementarydevices can be added to the liquid crystal device 1, if necessary.

As shown in FIGS. 1 and 2, the liquid crystal panel 2 includes, forexample, a first substrate 4 and a second substrate 5 bonded with oneanother through a seal member (not shown), and a liquid crystal layer 6including nematic liquid crystal molecules interposed between thesubstrates.

The first substrate 4 and the second substrate 5 include a firstsubstrate 4 a and a second substrate 5 a each formed of a plate memberhaving a light transmitting property, for example, a glass,respectively. As shown in FIG. 2, a first polarizing plate 7 and asecond polarizing plate 8 for polarizing incident light are bonded onthe outer surfaces of the first substrate 4 a and the second substrate 5a, respectively.

As shown in FIG. 3, a first absorption axis 7 a of the first polarizingplate 7 is perpendicular to a second absorption axis 8 a of the secondpolarizing plate 8. The absorption axis 7 a of the first polarizingplate 7 is equal to an initial alignment direction 9 a (hereinafter,simply referred to as “an alignment direction”) as a first direction ofliquid crystal molecules 9 of the liquid crystal layer 6. The firstdirection is an in-plane direction on a substrate surface.

As shown in FIG. 2, the first substrate 4 a includes an alignment film10 for allowing liquid crystalline compounds to be in mutually differentalignment states in the reflective display portion and in thetransmissive display portion, a phase difference layer 11 in whichpolymerized liquid crystal compounds are laminated so as to be formed inthe reflective display portion and in the transmissive display portion,a layer thickness adjusting layer 12 formed in the reflective displayportion, an alignment film 13 formed in the reflective display portionon the inner side (liquid crystal layer) thereof.

An alignment regulating force is applied to the alignment film 10 of theliquid crystalline compounds described above, using a rubbing processwith which, for example, polyimide is formed in the reflective displayportion and the transmissive display portion in different directionsusing a resist, or a photo-alignment technology.

The phase difference layer 11 is formed on the alignment film 10 (liquidcrystal side) subjected to the rubbing process by laminating thepolymerized liquid crystalline compounds and an giving them opticallyuniaxial property. In this way, the alignment direction of molecules 25(liquid crystal molecules of the liquid crystalline compound having apolymerizable group) of the phase difference layer 11 in a reflectivedisplay portion 11 a can be configured to be different from thealignment direction in a transmissive display portion 11 b. For example,an angle formed by the alignment directions is about 67.50.

The phase difference layer 11 is configured to have a film thickness orthe like so that retardation, for example, becomes about a halfwavelength in both the reflective display portion 11 a and in thetransmissive display portion 11 b. As shown in FIG. 3, for example, adirection 25 a of the molecules 25 is parallel to the alignmentdirection 9 a of the liquid crystal molecules 9 (that is, which areparallel and their directions are the same) in a top view (for example,when the liquid crystal panel 2 is viewed from above).

The alignment film 13 is formed so as to be close to the liquid crystallayer in the first substrate 4 a to cover the layer thickness adjustinglayer 12 in the reflective display portion and the phase differencelayer 11 in the transmissive display portion. For example, the alignmentdirection 9 a of the liquid molecule 9 is parallel to a direction of theabsorption axis 7 a of the first polarizing plate 7, as shown in FIG. 3.

As shown in FIGS. 1 and 2, for example, the second substrate 5 aincludes an alignment film 14, TFTs 15, gate lines 16 electricallyconnected to the TFTs 15, source lines 17, pixel electrodes 18 as firstelectrodes, common electrodes 19 disposed to be separated from the pixelelectrodes 18 as second electrodes, a resin layer 20, an insulatinglayer 21, a reflective layer 22, common electrode lines 23 stacked onthe liquid crystal layer.

The gate lines 16 and the source lines 17 are arranged alternately withone another, for example, as shown in FIG. 1. A plurality of the gatelines 16 are formed parallel to one another in an X direction so as tobe close to the liquid crystal layer in the second substrate 5 a. Inaddition, a plurality of the source lines 17 are formed parallel to a Ydirection so as to be close to the liquid crystal layer in the secondsubstrate 5 a.

As shown in FIG. 1, the pixel electrodes 18 are formed in a latticepattern, for example, on the liquid crystal side of the resin layer 20.In addition, the pixel electrodes 18 are electrically connected to theTFTs 15.

The common electrodes 19 are formed in the lattice pattern, for example,close to the liquid crystal side of the resin layer 20 so as to beseparated from and intersect with the pixel electrodes 18. In addition,the common electrodes 19 are electrically connected to the commonelectrode lines 23 through through-holes (not shown) formed in the resinlayer 20 and the insulating layer 21. When a voltage is applied to thepixel electrodes 18 and the common electrodes 19, a transverse electricfield is formed between the two lattice patterns. The pixel electrodes18 and the common electrodes 19 are made of, for example, indium tinoxide (ITO).

For example, as shown in FIG. 1, the reflective layer 22 is formedbetween the second substrate 5 a and the insulating layer 21 so as tooverlap with parts of the pixel electrodes 18 and the common electrodes19 in a top view, which are configured to intersect with one another inpixels surrounded by the gate lines 16 and the source lines 17.

The reflective layer 22 is made of a material such as aluminum whichreflects light. As shown in FIG. 2, incident light B (B in FIG. 2) isreflected so that a reflective display portion C (C in FIG. 2) isconfigured. In addition, a region in which the pixel electrodes 18 andthe common electrodes 19 are formed, separate from the reflectivedisplay portion C is a transmissive display portion D (D in FIG. 2) inwhich light is transmitted. The transmissive display portion D allowslight from the illuminating device 3 described below to be transmittedand to be emitted from the first polarizing plate 7.

For example, as shown in FIG. 2, an alignment film 14 is formed so as tocover the pixel electrodes 18 and the common electrodes 19 and to be theclosest to the liquid crystal layer in the second substrate 5 a. Thealignment direction of the liquid crystal molecules 9 is configured tobe parallel to the absorption axis 7 a of the first polarizing plate 7,for example, as shown in FIG. 3.

On the sides of the liquid crystal layer adjacent to the first substrate4 a and the second substrate 5 a, an underlying layer, a coloring layer,a light-shielding layer and the like (not shown), are formed, ifnecessary.

For example, as shown in FIG. 2, the illuminating device 3 is abacklight unit for supplying light to the liquid crystal panel 2 andincludes a light source, a light guide plate 24, and the like (notshown).

Operation of Liquid Crystal Device

Next, how light travels inside the liquid crystal panel in operation ofthe liquid crystal device 1 with the above-described configuration, andmore particularly, a black display of the transmissive display portion Dwill be described.

FIG. 4 is a diagram for explaining how light travels in the first andsecond polarizing plates, the liquid crystal layer, and the phasedifference layer according to the first embodiment. FIG. 5 is a diagramfor explaining the absorption axis of the polarizing plate, the liquidcrystal molecules, and a direction of the molecules of the phasedifference layer when a liquid crystal panel is viewed in an obliquedirection according to the first embodiment.

For example, when a voltage is not applied to the pixel electrodes 18and the common electrodes 19, as shown in FIG. 2, the light incidentfrom the light guide plate 24 of the illuminating device 3 to the secondpolarizing plate 8, as shown in FIG. 4, becomes linearly polarized lightin a direction substantially perpendicular to the direction of theabsorption axis 8 a of the second polarizing plate 8 (polarization state1).

When the light in polarization state 1 is incident to the liquid crystallayer 6, as shown in FIG. 4, the initial alignment direction 9 a of theliquid crystal molecules 9 is perpendicular to the direction of theabsorption axis 8 a of the second polarizing plate 8. Accordingly, theincident linearly polarized light is not affected and is transmitted soas to be incident to the phase difference layer 11 (polarization state2).

Subsequently, when the light in polarization state 2 is incident to thephase difference layer 11, as shown in FIG. 4, a director 25 a of themolecules 25 of the phase difference layer 11 is parallel to thealignment direction 9 a of the liquid crystal molecules 9. Accordingly,the incident linearly polarized light in the alignment direction 9 a ofthe liquid crystal molecules 9 without being affected is incident to thefirst polarizing plate 7 (polarization state 3).

When the light in polarization state 3 is incident to the firstpolarizing plate 7, as shown in FIG. 4, the direction of the absorptionaxis 7 a of the first polarizing plate 7 is equal to the polarizationdirection of the linearly polarized incident light. The incident lightis absorbed, and thus not emitted from the first polarizing plate 7 torealize black display.

The light described above has been described in a top view, but whenobliquely viewed, the light can be described from a different viewpoint.Hereinafter, how the light travels in an oblique view will be described.

First, the liquid crystal molecules 9 and the molecules 25 of the phasedifference layer 11 have a predetermined pretilt angle with respect to,for example, a first substrate surface so as to be inclined. Forexample, the pretilt angle of the molecules 25 is about 3°.

For example, as shown in FIG. 5, the alignment direction 9 a of theliquid crystal molecules 9 is inclined by the pretilt angle in theoblique view from the upper side, compared to in the top view. Inaddition, the light becomes linearly polarized light with a deviatedaxis. As a result, polarization state 2 becomes polarization state 21.

At this time, the director 25 a of the molecules 25 in the transmissivedisplay portion 11 b of the phase difference layer 11 is parallel to thealignment direction 9 a of the liquid crystal molecules 9 in the topview. Accordingly, as shown in FIG. 5, in the oblique view, an angleformed by a direction of the major axis of the molecules 25 and thedirection of the major axis of the liquid crystal molecules 9 becomessmall.

With such a configuration, the light emitted from the phase differencelayer 11 becomes elliptically polarized light. However, the minor axisof the ellipse is considerably smaller than the major axis and lightleaked from the first polarizing plate 7 can be neglected. Accordingly,light leakage in the dark display in an oblique direction can be furtherprevented, thereby improving the wide viewing angle.

For example, in terms of the Poincare sphere, the fact that the angleformed by the direction of the major axis of the molecules 25 and thepolarization axis of the linearly polarized light being transmittedthrough the liquid crystal layer 6 becomes smaller means that the sphereis a little swollen from the equator due to the polarization changecaused by the phdse difference layer 11 in the equator, thereby becomingelliptically polarized light close to linearly polarized light.

The operation of the liquid crystal device 1 has been described.

According to the above-described embodiment, the phase difference layer11 is formed in the transmissive display portion C and the reflectivedisplay portion D of the liquid crystal layer in the first substrate 4and the second substrate 5. Accordingly, it is possible to eliminatedifficulty in patterning the phase difference layer 11 only in thereflective display portion in the known example, thereby reducing cost.

Since the alignment directions of the molecules 25 in the phasedifference layer 11 are different in the transmissive display portion 11b and the reflective display portion 11 a, effect of the phasedifference layer 11 in the transmissive display portion D can beminimized.

At least in the transmissive display portion D, the director 25 a of themolecules 25 in the phase difference layer 11 is parallel to thealignment direction 9 a of the liquid crystal molecules 9 in thesubstrate surface. Accordingly, even when viewed in the obliquedirection, the light leakage is reduced in the black display. Forexample, by allowing the director 25 a to be parallel to the alignmentdirection 9 a, in terms of the Poincare sphere, the sphere is lessswollen from the equator due to the phase difference layer 11. In thisway, the polarization state become an elliptical state to being a linearstate, thereby further preventing the light leakage in the blackdisplay. Accordingly, it is possible to obtain a wider viewing angleproperty.

The absorption axis 7 a of the first polarizing plate 7 is parallel tothe alignment direction 9 a of the liquid crystal molecules 9.Accordingly, when a voltage is not applied between the pixel electrodes18 and the common electrodes 19, the light being transmitted through theliquid crystal layer 6 is absorbed by the first polarizing plate 7. As aresult, a completely black display is possible.

An angle between the alignment direction of the molecules 25 in thephase difference layer 11 of the transmissive display portion D and thealignment direction of the reflective display portion C is about 67.5°.Accordingly, a retardation of the liquid crystal layer 6 in thereflective display portion C is about a quarter wavelength, therebyobtaining a better black display.

The retardation of the liquid crystal layer 6 is about a half wavelengthin the transmissive display portion D and the retardation of the liquidcrystal layer 6 is about a quarter wavelength in the reflective displayportion C. Accordingly, it is possible to obtain the black display inboth the transmissive display portion D and the reflective displayportion C by adjusting a phase difference of a quarter wavelength causedbetween the transmissive display portion D and the reflective displayportion C.

The retardation of the liquid crystal layer 11 is about a halfwavelength in both the transmissive display portion D and the reflectivedisplay portion C. Accordingly, the light in the reflective displayportion C is made to become circularly polarized light or ellipticallypolarized light by the liquid crystal layer 6. In addition, when thelight is reflected and incident to the first polarizing plate 7, thelight becomes the linearly polarized light in the direction of theabsorption axis. In this way, it is possible to more reliably obtain theblack display.

The phase difference layer 11 is formed of the polymerized liquidcrystalline compound. Accordingly, since it is easy to change thealignment direction in the transmissive display portion D and thereflective display portion C, it is possible to obtain the black displaywith no light leakage.

Hereinafter, examples will be described in order to discuss a wideviewing angle characteristic of the liquid crystal device according tothe invention.

Example 1

FIG. 6 is a diagram for explaining the viewing angle characteristic in ablack display. In FIG. 6, the center of a circle corresponds to thefront side of the liquid crystal device (in a right top view). Inaddition, the more a view is moved away from the center, the more anangle increases. A region E is a region where the light leakage is thesmallest and regions F, G, H and I (oblique lines in the drawing) areregions where the light leakage increases. That is, the region I is aregion where the light leakage is the largest. Another viewing anglecharacteristic that will be described below is also applied.

In Example 1, as shown in FIG. 6, the liquid crystal device 1 is used.That is, the direction of the absorption axis 7 a of the firstpolarizing plate 7 shown in FIG. 3 is parallel to the alignmentdirection 9 a of the liquid crystal molecules 9 and the director 25 a ofthe molecules 25 in the phase difference layer 11 is parallel to thealignment direction 9 a of the liquid crystal molecules 9 in the topview. It was proven that the light leakage was considerably small evenin the regions G located in four different directions away from thecenter and it was possible to obtain the wide viewing anglecharacteristic in which the light leakage in the black display is small.

Example 2

FIG. 7 is a diagram for explaining the absorption axis of the polarizingplate and the directions of the liquid crystal molecules and themolecules in the phase difference layer. FIG. 8 is a diagram forexplaining the viewing angle characteristic when the direction of themolecules in the phase difference layer is aligned in a reversedirection. FIG. 9 is a diagram for explaining the absorption axis of thepolarizing plate and the directions of the liquid crystal molecules andthe molecules in the phase difference layer when viewed in the obliquedirection.

Example 2 is different from Example 1 in that there is provided a liquidcrystal device in which the director 25 a of the molecules 25 in thephase difference layer 11, as shown in FIG. 7, is directed to beanti-parallel (parallel in an opposite direction) to the alignmentdirection 9 a of the liquid crystal molecules 9 in the top view.

In Example 2, as shown in FIG. 8, strong light leakage I occurred in tworegions located away from the center on the right side, but weak lightleakage G just occurred in two regions located away from the center onthe left side. Accordingly, a result obtained in Example 2 was notbetter than that obtained in Example 1, but it was proven that the lightleakage was prevented to some extent, thereby obtaining the wide viewingangle characteristic.

The reason the wide viewing angle characteristic in Example 2 is notbetter than that in Example 1 is that, as shown in FIG. 9, theanti-parallel major direction of the molecules 25 in the phasedifference layer 11 seems to have a large angle from the linearlypolarized light deviated in the oblique view by change in polarizationchange in the liquid crystal layer 6. In terms of the Poincare sphere,the sphere is swollen from the equator to approximately circularlypolarized light. That is, that is considered to be because considerablelight must leak from the first polarizing plate 7 in order for the lightas elliptically polarized light close to the circularly polarized lightto be incident to the first polarizing plate 7.

Example 3

FIG. 10 is a diagram for explaining the absorption axis of thepolarizing plate and the directions of liquid crystal molecules and themolecules in the phase difference layer. FIG. 11 is a diagram forexplaining the viewing angle characteristic when the absorption axes ofthe first and second polarizing plates are formed vice versa.

Example 3 is different from Example 1 in that, as shown in FIG. 10, thedirection of the absorption axis 7 a of the first polarizing plate 7 ofthe liquid crystal device 1 is perpendicular to the alignment direction9 a of the liquid crystal molecules 9 and the direction of theabsorption axis 8 a of the second polarizing plate 8 is parallel to thealignment direction 9 a of the liquid crystal molecules 9.

In Example 3, as shown in FIG. 11, slightly strong light leakage Hoccurred in two regions away from the center on the right side, but weaklight leakage G just occurred in two regions away from the center on theleft side. Accordingly, a result obtained in Example 3 was not betterthan that obtained in Example 1, but it was proven that the lightleakage was considerably prevented, thereby obtaining the wide viewingangle characteristic.

Example 4

FIG. 12 is a diagram for explaining the absorption axis of thepolarizing plate and the direction of the liquid crystal molecules andmolecules in the phase difference layer. FIG. 13 is a diagram forexplaining the viewing angle characteristic when the direction of themolecules in the phase difference layer is directed oppositely and theabsorption axes of the first and the second polarizing plates areconfigured to be formed vice versa.

Example 4 is different from Example 1 in that, as shown in FIG. 12, thedirection of the absorption axis 7 a of the first polarizing plate 7 ofthe liquid crystal device 1 is perpendicular to the alignment direction9 a of the liquid crystal molecules 9, the direction of the absorptionaxis 8 a of the second polarizing plate 8 is parallel to the alignmentdirection 9 a of the liquid crystal molecules 9, and the director 25 aof the molecules 25 of the phase difference layer 11 is anti-parallel tothe alignment direction 9 a of the liquid crystal molecules 9 in the topview.

In Example 3, as shown in FIG. 13, the strong light leakage I occurredin two regions away from the center on the left side, but weak lightleakage F just occurred in two regions away from the center on the rightside. Accordingly, a result obtained in Example 4 was not better thanthat obtained in Example 1, but it was proven that the light leakage wasprevented to some extent, thereby obtaining the wide viewing anglecharacteristic.

Comparative Example 1

FIG. 14 is a diagram for explaining the absorption axis of thepolarizing plate and the direction of liquid crystal molecules andmolecules in the phase difference layer. FIG. 15 is a diagram forexplaining the viewing angle characteristic when the direction of themolecules in the phase difference layer is perpendicular to thedirection of the liquid crystal molecules.

Comparative Example 1 is different from Example 1 in that there isprovided a liquid crystal device in which the director 25 a of themolecules 25 in the phase difference layer 11, as shown in FIG. 14, isperpendicular to the alignment direction 9 a of the liquid crystalmolecules 9 in the top view.

In Comparative Example 1, as shown in FIG. 15, the strong light leakageI occurred in four regions on the right and the left sides until regionsclose to the center. Accordingly, the light leakage in ComparativeExample 1 was more than that in Examples 1 to 4. It was proven that thewide viewing angle characteristic in the black display of a transverseelectric field mode may deteriorate if the director 25 a of themolecules 25 in the phase difference player 11 is configured to beperpendicular to the alignment direction 9 a of the liquid crystalmolecules 9 in the top view.

Comparative Example 2

FIG. 16 is a diagram for explaining the absorption axis of thepolarizing plate and the direction of the liquid crystal molecules andthe molecules in the phase difference layer. FIG. 17 is a diagram forexplaining the viewing angle characteristic when the direction of themolecules in the phase difference layer is perpendicular to thedirection of the liquid crystal molecules and the absorption axes of thefirst and second polarizing plates are formed vice versa.

Comparative Example 2 is different from Example 1 in that, as shown inFIG. 17, there is provided a liquid crystal device in which thedirection of the absorption axis 7 a of the first polarizing plate 7 ofthe liquid crystal device 1 is perpendicular to the alignment direction9 a of the liquid crystal molecules 9, the absorption axis 8 a of thesecond polarizing plate 8 is parallel to the alignment direction 9 a ofthe liquid crystal molecules 9, and the director 25 a of the molecules25 in the phase difference layer 11 is perpendicular to the alignmentdirection 9 a of the liquid crystal molecules 9 in the top view.

In Comparative Example 2, as shown in FIG. 17, the strong light leakageI or the slightly strong light leakage H occurred in two regions awayfrom the center on the upper side. The light leakage in ComparativeExample 2 was more than that in Example 1 or 3, even though the lightleakage in Comparative Example 2 was less than that in ComparativeExample 1. In addition, it was proven that the wide viewing anglecharacteristic in the black display of the transverse electric fieldmode may deteriorate if the director 25 a of the molecules 25 in thephase difference layer 11 was perpendicular to the alignment direction 9a of the liquid crystal molecules 9 in the top view.

Among Examples 1 to 4 and Comparative Examples 1 and 2, the most exampleshowing the least light leakage and the most wide viewing anglecharacteristic is Example 1, the next most example is Example 3 andComparative Example 2, the next is Examples 2 and 4. In addition, anexample showing the most light leakage and the least wide viewing anglecharacteristic is Comparative Example 1.

As described above, in order to allow the light leakage to be smaller inthe black display of the transverse electric field, it is desirable thatthe director 25 a of the molecules 25 in the phase difference layer 11is parallel to the alignment direction 9 a of the liquid crystalmolecules 9 in the top view and the direction of the absorption axis 7 aof the first polarizing plate 7 is parallel to the alignment direction 9a of the liquid crystal molecules 9.

When the director 25 a of the molecules 25 in the phase difference layer11 is parallel to the alignment direction 9 a of the liquid crystalmolecules 9 in the top view, the direction of the absorption axis 7 a ofthe first polarizing plate 7 is perpendicular to the alignment direction9 a of the liquid crystal molecules 9 and the direction of theabsorption axis 8 a of the second polarizing plate 8 is parallel to thealignment direction 9 a of the liquid crystal molecules 9 (like Example3), it was proven that the light leakage is considerably small and thewide viewing angle characteristic can be obtained.

Alternatively, when the director 25 a of the molecules 25 in the phasedifference layer 11 is unavoidably configured to perpendicular to thealignment direction 9 a of the liquid crystal molecules 9 in the topview, the direction of the absorption axis 7 a of the first polarizingplate 7 can be configured to be perpendicular to the alignment direction9 a of the liquid crystal molecules 9 and the direction of theabsorption axis 8 a of the second polarizing plate 8 can be configuredto be parallel to the alignment direction 9 a of the liquid crystalmolecules 9. In this case, it was proven that a considerable good wideviewing angle in the black display of the transverse electric field modecan be obtained.

Second Embodiment

Next, a liquid crystal device according to a second embodiment of theinvention will be described. The second embodiment is different from thefirst embodiment in that an insulating layer is formed between the pixelelectrodes and the common electrodes, which will be described. In thefollowing description, the same reference numerals are given to the samecomponents as those in the first embodiment and the description will beomitted or simplified.

FIG. 18 is a schematic top view illustrating a liquid crystal deviceaccording to a second embodiment of the invention. FIG. 19 is aschematic sectional view illustrating the liquid crystal device takenalong the line J-J shown in FIG. 18. FIG. 18 shows a second substrate inwhich an alignment film is removed for descriptive convenience.

Configuration of Liquid Crystal Device

In a liquid crystal device 101, for example, as shown in FIGS. 18 and19, a first base 5 a includes an alignment film 14 on a side of a liquidcrystal layer, TFTs 15, gate lines 16 electrically connected to the TFTs15, source lines 17, pixel electrodes 118 as first electrodes, aninsulating layer 120, common electrodes 119 as second electrodesdisposed so as to overlap with the pixel electrodes 118 through theinsulating layer 120, insulating layer 121, common electrode lines 123electrically connected to the common electrodes 119, etc.

For example, as shown in FIG. 19, some of the common electrode lines 123overlap with the second substrate 5 a on the side of the liquid crystallayer through the common electrodes 119 and the insulating layer 121. Inaddition, the common electrode lines 123 are electrically connected tothe common electrodes 119 through through-holes (not shown) formed inthe insulating layer 121. Moreover, the common electrode lines 123 aremade of, for example, aluminum and as shown in FIG. 19, a part on whichincident light B is reflected is a reflective layer 122. Accordingly, areflective display portion C is formed in a region in which the commonelectrode lines 123 overlap with the common electrodes 119 and the pixelelectrodes 118. Of course, a reflective layer may be formed separatelyfrom the common electrode lines 123.

As shown in FIG. 19, some of the common electrodes 119 overlap with, forexample, the common electrode lines 123 through the insulating layer121. In addition, the common electrodes 119 made of, for example, indiumtin oxide (ITO) are formed on the insulating layer 121 on the side ofthe liquid crystal layer so as to substantially overlap with the pixelelectrodes 118 through the insulating layer 120.

As shown in FIGS. 18 and 19, for example, the pixel electrodes 118include slits 118 a parallel to the gate lines 16 and extension portion118 b for forming the slits 118 a. Accordingly, when a voltage is,applied to the pixel electrodes 118 and the common electrodes 119, anelectric field considerably curved toward the common electrodes 119 isformed through the insulating layer 120 by the extension portions 118 band the slits 118 a.

The pixel electrodes 118 are not limited to the case where the slits areformed in the above-described manner, but may be formed in a latticepattern on a side of the liquid crystal layer in the insulating layer120.

Operation of Liquid Crystal Device

Next, the way how light travels in a liquid crystal panel when theliquid crystal device 101 with the above-described configurationoperates is the almost same that according to the first embodiment, andthus will be omitted.

In this way, according to the second embodiment, the second substrate 5is configured to have the insulating layer 120 between the pixelelectrodes 118 and the common electrodes 119. Accordingly, when avoltage is applied, the electric field formed between the pixelelectrodes 118 and the common electrodes 119 is considerably curved andthe alignment direction of the liquid crystal molecules 9 in theelectrodes is controlled. In this way, it is possible to obtain thewider viewing angle characteristic.

Third Embodiment Electronic Apparatus

Next, an electronic apparatus including the above-described liquidcrystal device 1 or 101 will be described according to a thirdembodiment of the invention.

FIG. 20 is a schematic diagram illustrating an outer appearance of acellular phone according to a third embodiment of the invention. FIG. 21is a schematic diagram illustrating an outer appearance of a personalcomputer.

For example, as shown in FIG. 20, a cellular phone 500 includes, forexample, the liquid crystal device 1 on an outer frame with a pluralityof operation buttons 571, an ear piece 572, and a mount piece 573.

As shown in FIG. 21, a personal computer 600 includes a main body 682with keyboards 681 and a liquid crystal display portion 683. The liquidcrystal display portion 683 includes, for example, the liquid crystaldevice on an outer frame 1.

The electronic apparatuses, even though other elements except for theliquid crystal device 1 are not shown, include various circuits such asa display information output source or a display information processingcircuit, a power source circuit for supplying electric power to thecircuits, etc.

For example, in the personal computer 600, display images are displayedon the liquid crystal device 1 by supplying display signals generated bya signal generating unit on the basis of information input from thekeyboards 681.

According to the third embodiment, there is provided the liquid crystaldevice 1 which can easily obtain the same effect as that obtained in acase where the phase difference layer is formed only in the reflectivedisplay portion C, and improve the wide viewing angle by furtherpreventing the light leakage in the black display.

In particular, since the wide viewing angle and high color reproductionhave been demanded in the portable electronic apparatuses describedabove, the present invention which can realize high display quality atlow cost is advantageous.

Examples of the electronic apparatus include a touch panel mounted withanother liquid crystal device, a projector, a monitor direct view-typevideo tape recorder, a car navigation apparatus, a pager, an electronicpocket book, a calculator, and the like. In addition, it is needless tosay that as a display portion of the various electronic apparatuses, forexample, the liquid crystal device 1 or 101 described above can beapplied.

The invention is not limited to the above-described embodiment, but maybe modified to various forms in the range of technique spirit of theinvention.

For example, in the above-described embodiment, as an example of theliquid crystal device, a thin film transistor element active matrix-typeliquid crystal device has been described, but the invention is notthereto. For example, a thin film diode element active matrix-type orpassive matrix-type liquid crystal device may be used. Even in thevarious types of liquid crystal device, since the light leakage in theblack display is small, the wide viewing angle characteristic can beimproved.

It should be understood that various changes and modifications to thepresently preferred embodiments described herein will be apparent tothose skilled in the art. Such changes and modifications can be madewithout departing from the spirit and scope of the present subjectmatter and without diminishing its intended advantages. It is thereforeintended that such changes and modifications be covered by the appendedclaims.

1. A liquid crystal device comprising: a liquid crystal layer interposedbetween a first substrate and a second substrate; a plurality of pixelseach having a transmissive display portion and a reflective displayportion; first and second electrodes formed on the second substrate;liquid crystal molecules in the liquid crystal layer are aligned in afirst direction in a plane of the substrate; and a phase differencelayer having molecules, which are inclined in the plane of the first orsecond substrate and are aligned in directions different from oneanother in the transmissive display portion and the reflective displayportion, is formed on a surface of the first or second substrate opposedto the liquid crystal layer, wherein a director of the molecules of thephase difference layer is aligned in a second direction parallel to thefirst direction at least in the plane of the transmissive displayportion, and wherein the second substrate has an insulating layerbetween the first and second electrodes.
 2. An electronic apparatuscomprising: a liquid crystal device including a liquid crystal layerinterposed between a first substrate and a second substrate, a pluralityof pixels each having a transmissive display portion and a reflectivedisplay portion, first and second electrodes formed on the secondsubstrate, liquid crystal molecules in the liquid crystal layer arealigned in a first direction in a plane of the substrate, and a phasedifference layer having molecules, which are inclined in the plane ofthe first or second substrate and are aligned in directions differentfrom one another in the transmissive display portion and the reflectivedisplay portion, is formed on a surface of the first or second substrateopposed to the liquid crystal layer, wherein a director of the moleculesof the phase difference layer is aligned in a second direction parallelto the first direction at least in the plane of the transmissive displayportion.